Aluminum wire has been utilized for many years in such applications as overhead electricity transmission lines due to its desirable combination of relatively high conductivity and low weight. Since the most desirable attribute of such wire is the conductivity, the most popular form of aluminum for this purpose has been that alloy formerly known as EC aluminum and now known by its Aluminum Association Registration No. 1350. This particular aluminum alloy contains small amounts of silicon and iron in a high purity aluminum base to provide a wire of high conductivity but with higher strength than ultra-pure aluminum.
Unfortunately, since this particular aluminum alloy itself requires the use of a high purity aluminum as the base material for the alloy, products produced from this metal have tended to increase in cost so as to lower the benefit/cost ratio of aluminum over other materials.
Various other aluminum alloys have been formulated as replacement materials for Alloy 1350. For example, U.S. Pat. No. 3,278,300 discloses an aluminum base alloy containing iron and rare earth elements which is particularly useful for electrical conductors. This particular alloy system may also contain such elements as zirconium and magnesium. The particularly preferred rare earth elements are the combination of elements known as mischmetal. The influence of mischmetal upon aluminum alloy conductors is also discussed in an article by Venkatesan et al. in the September, 1970 issue of Metallurgical Transactions on Pages 2638-2641. In this article entitled "Effect of Misch Metal and Ferrocerium Additions on the Properties of 24 Gage Aluminum Wires", the addition of up to 3% mischmetal in aluminum increases the strength of the resulting alloy while decreasing its electrical conductivity. Above this 3% level, both the strength and conductivity properties suffer. The aluminum base may contain small percentages of Mn, Ti, V, Cr, Fe, Cu and Si. Mischmetal has also been contemplated as an addition to aluminum alloys for conductor applications and also for aluminum casting alloy applications as indicated in "Recent Applications of the Rare Earth Metals in Nonferrous Metallurgy" by I. S. Hirschhorn in the October, 1970 issue of the Journal of Metals on Pages 40-43. None of these particular references teaches the alloy system contemplated by the present invention.
Therefore, it is a principal object of the present invention to provide an alloy which exhibits higher electrical conductivity than commercially utilized aluminum.
It is a further object of the present invention to provide an alloy which presents equivalent conductivity to commercial aluminum alloys while utilizing lower purity grades of aluminum as the base material therein, such as commercial purity aluminum.
It is another object of the present invention to provide an alloy as aforesaid which exhibits high electrical conductivity properties while utilizing grades of aluminum in which some normal impurity levels of certain elements are enhanced for strength properties.
It is another object of the present invention to provide an alloy as aforesaid which improves the conductivity of conductor grade aluminum alloys in the cold worked, partially annealed or fully annealed condition.
Further objects and advantages of the present invention will become apparent from a consideration of the following specification.